Ted Jackson / The Times-PicayuneB.J. Morgan and his dog Hank walk the levee as they enjoy the dog play area and the trees along the levee near the Riverbend section and the Mississippi River in New Orleans earlier this month. The mature line of trees runs afoul of an Army Corps of Engineers vegetation policy, previously ignored but now being aggressively enforced, that prohibits trees within 15 feet of levees and floodwalls.

Some 500 trees along the Mississippi River in East Jefferson and New Orleans ­-- and even the English ivy that has covered a French Quarter floodwall for decades -- are the next targets of a controversial Army Corps of Engineers vegetation policy that likely will require their removal.

Most of the trees are located behind homes that back up to the river in River Ridge, Harahan and Kenner, but a highly visible line of mature trees also flanks the western edge of the unofficial dog park along Leake Avenue, a clover-and-grass-covered levee slope long used by residents of Uptown New Orleans and the canines who walk them.

All of the trees, as well as vines blanketing the floodwall that separates the Moon Walk and parking lot east of Jax Brewery from Café du Monde and other iconic French Quarter establishments north of the wall, are now listed on annual corps levee inspection reports as "encroachments" in need of removal.

Local levee districts have been advised not to start cutting yet, however, as decision-makers at corps headquarters continue grappling with the fallout from their post-Hurricane Katrina decision to start aggressive enforcement of a previously ignored policy that prohibited trees within 15 feet of levees and floodwalls.

Not only has the policy raised the ire of naturalists, it has also spawned complex real estate and environmental issues that must be addressed.

When asked for advice on how to proceed, a corps operations supervisor in New Orleans recently told a group of regional levee commissioners and district executives that he wouldn't advise cutting riverside trees until there is further word from headquarters.

"I can't speak on behalf of the whole corps ... but I wouldn't move just yet," Jerry Colletti, assistant operations chief for the district, told the group. "We may know some more after a meeting we're having in a few weeks ... or by the end of the year.

"Trees are going to be an issue for a long time, and we've asked (headquarters) for a better waiver system and the ability to use some engineering judgment when it comes to deciding what needs removing in our districts," he said.

"I'd say don't do anything yet until we hear something else from them."

'Minimally acceptable'

Colletti and corps geotechnical engineer Rich Varuso said agency inspectors have no choice but to note the existence of trees and other growth that seems to violate the vegetation policy. But they said inspectors aren't lowering the overall ratings the levee systems are given.

"The trees are noted and rated 'minimally acceptable,' and while I know the word 'minimal' is a red flag that raises concern, all it really means is that it's something for us to monitor," he said. "It doesn't mean that the levee isn't capable of functioning as designed."

If a tree or any other obstruction is discovered in a levee section proper, the tree is ordered removed.

But the corps isn't yet ordering that trees and shrubs be removed from the 15-foot-wide vegetative-free zones that are supposed to be maintained outside levee toes and floodwalls.

Corps commanders say the primary goal of vegetation regulations is to provide access and unobstructed views of levees and floodwalls in order to inspect them properly, detect developing trouble, perform required maintenance, make needed improvements and carry out emergency flood-fighting.

A dog runs to catch up to his master as they enjoy the dog play area and the trees along the Mississippi River levee near the Riverbend in New Orleans earlier this month.Secondarily, they say, maintaining a grass-only system minimizes the presence of trees that, if blown over during a hurricane, could dislodge roots or rootballs, possibly destabilizing a levee or floodwall with tragic consequences.

A post-Katrina policy

A position paper issued by corps headquarters in April 2007 laid out its case publicly for strengthening vegetative regulations and mandating across-the-board enforcement with little hope of getting a waiver to sidestep them.

Ironically, some corps districts and levee districts have not only allowed trees, fences, swimming pools and even the occasional structure to go up in these "vegetation free zones, " the agencies even helped plant trees as part of community beautification programs. And not until after Katrina did corps levee inspectors even start to identify large trees on levees as an issue for correction, the corps' 2007 position paper noted.

But the document also made clear that in the future, the cost of noncompliance would be steep: Federal aid will be withheld in response to any future floods, and offending levee systems risk decertification and the loss of participation in the federal flood insurance program.

Corps officials said there's no chance that such punitive action would be taken against local levee districts for not cutting trees at this point.

There is still no certainty as to what role, if any, large trees blown over by Katrina might have played in floodwall breaches that led to the catastrophic flooding of New Orleans and parts of East Jefferson.

Lessons learned since then have revealed floodwall design deficiencies, including shallow foundations, that could well account for all the failures. But large trees growing in levee slopes near the major breaches were uprooted in the storm.

Tests explore trees' danger

In an effort to help resolve some of the dueling scientific theories regarding the marriage of trees and levees, the corps last year tasked the Army's own Engineer Research and Development Center to launch new research into the effects of woody vegetation on levee performance. The project, which includes computer modeling and hands-on test sites in New Orleans and nine other cities in eight states, is scheduled to finish up this year.

In addition, the Army facility staff is also collaborating in research being led by a California consortium hoping to find a way to ensure levee safety while saving the last remnants of the riparian forest that once lined rivers in the Central Valley.

"This is a work in progress, and we're trying to be consistent, " Varuso said. "But on levees that have been around for a while, there are complicating issues. It takes time."

The push to eliminate everything but grass on or around federal levees and floodwalls was fueled by Katrina, and well before the position paper was ever published, the crackdown on trees was in full swing along hurricane protection levees on Lake Pontchartrain and floodwalls in New Orleans, Metairie and Kenner.

By the time it was over, some 5,000 trees had been cut, many of them along the breached London and 17th Avenue canals, and lawsuits filed as a result of the removals are still working their way through the courts.

Varuso and Colletti said it was necessary to cut trees off the levees, berms and adjoining 15-foot zones because of the Katrina experience.